This proposal is for a one-time scientific conference entitled, "Extinction: The Neural Mechanisms of Behavior Change", to be held in Ponce, Puerto Rico, February 2-6, 2005. Extinction is the decreased expression of conditioned responding that occurs when a conditioned stimulus is repeatedly presented in the absence of the unconditioned stimulus. Deficits in extinction learning are thought to underlie anxiety disorders (such as PTSD) and addictive behavior, both of which involve persistent emotional responses that are no longer appropriate. Understanding the neural mechanisms of extinction could lead to novel behavioral and pharmacological therapies. This would be the first conference ever held on the topic of extinction, a new field which has undergone rapid growth in the past 4 years. This is a unique opportunity to bring together the entire field of researchers (32 basic and clinical scientists) to resolve controversies and encourage a translational approach for future research. The conference will consist of 8 sessions: 1) Amygdala mechanisms in extinction of aversive conditioning, 2) Prefrontal mechanisms in extinction of aversive conditioning, 3) Contextual modulation of extinction, 4) Molecular mechanisms of extinction: Prefrontal-amygdala system, 5) Molecular mechanisms of extinction: Other systems, 6) Extinction of appetitive conditioning and addiction, 7) Neural substrate of extinction in humans, 8) Extinction as a therapeutic tool. Each session will be followed by questions from local students and an extended general discussion. Therewill also be evening debates on controversial themes, and a poster session. The conference will have a high degree of women & minority participation at all levels (speakers, organizing committee, attendees), and will provide students in Puerto Rico with unprecedented access to experts in the field. Travel fellowships for students from neighboring countries in Latin America will be provided. The findings will be disseminated in a special issue of the journal Biological Psychiatry, which will reach those most interested in the translational focus of the meeting. Thus, the conference should have considerable scientific impact, as well as serving a capacity-building function in the region. [unreadable] [unreadable]